Coated iron-alloy material



Patented Oct. 31, 1922.

UNITED STATES PATENT OFFICE.

WESLEY J. BECK AND JAMES A. AUPPERLE, 0F MIDDLETOWN, OHIO, ASSIGNORS TO THE AMERICAN ROLLING MILL COMPANY, OF MIDDLETOWN, OHIO, A CORPORA- TION OF OHIO.

COATED IRON-ALLOY MATERIAL.

No Drawing.

7'0 (1]? whom it may concern:

Be it known that we, \VEsLEY J. BECK and JAMES A. Arrrrnnnn, citizens of the United States, and residents of Middletown, in the county of Butler and State of Ohio, have invented a certain new and useful Coated Iron-Alloy Material, of which the following is a clear and exact description.

Our invention relates to iron alloy sheets, formed products. bars or other material which admits of being cold-rolled, said alloy sheets composed in part of silicon in an amount not sufficient to impair workability. It has as its object the surfacing of such irox'tlicon material with a coating of silicon compounds imbedded or impregnated 1n the surface of the sheet, which with the lapse of time finally produces an air and moistureproof coating.

As stated in copending applications filed by us on even date herewith Serial Nos. 283.579 and 283,581, to which reference is hereby made for a fuller description, we have found that silicon alloys of iron containing silicon in amounts not sufficient to impair workability are extremely valuable when exposed to natural corrosion, because the silicon acts as a deoxidizer and prevents the oxide which forms on the surface of the metal from passing into the highest state of oxidation, such oxides consisting essentially of red ferric oxide (Fe o which ordinarily are coarse grained and loosely adherent to the metal. When silicon acts as a deoxidizer in the formation of oxide on the surface of the metal at atmospheric temperatures, the oxide formed is of velvety texture, black in color, and firmly adherent to the metal. The coating formed being of a cementitious nature, impenetrable to air and moisture, and, furthermore, if this coatin which consists essentially of magnetic oxide of iron (FeO. rep.) together with silicon compounds becomes broken, the silicon tends to produce the magnetic oxide of iron (FeO. Fe replacing, the coating where broken in the same manner as originally produced.

In the process of rolling such iron alloys containing silicon in substantial quantities, there is produced on the surface of the heated iron exposed to the air during rolling, a thin oxide coating. \Ve have found that this thin coating of oxide of iron and Serial No. 283,580.

silicon compounds is, in the usual process of annealing, reduced to a loose film, consisting essentially of metallic iron, which has not been reincorporated with the body of the sheetmetal, together with said silicon compounds. Thus the finished sheet is usually covered with a thin film or skin of metal which will eventually scale off, and which is always objectionable from an appearance standpoint, but chiefly so where the sheet is to be painted soon after being placed in service \Vhile herein referring to sheets we merely use this term for convenience, as any shape capable of being coldrolled is intended.

lVe have found that when a sheet of ironsilicon alloy containing silicon in quantities not sufficient to impair workability, preferably from five-tenths per cent up to four and five-tenths per cent, or higher under special conditions, is pickled according to the usual practice, and then given one or more passes through the cold rolls, certain chemical and physical actions result which produce a most desirable product.

Our preferred pickling bath is a solution containing approximately five per cent of sulphuric acid. the sheets being allowed to remain in the hot pickle until clean. The time and temperature of pickling are those usually employed when sheets are galvanized. \Ve have found that the pickling of these iron-silicon alloys dissolves the iron and leaves the silicious compounds upon the surface of the sheet which are not easily removed in the subsequent operations when the sheets are rinsed in water.

\V e then preferably dry the sheets, although they may be left wet, and give them one or more passes through the cold rolls in the usual manner of cold-rolling, thus impregnating the surface of the Sheet with the silicious material deposited thereon. forming a smooth, dense, cementitious coating which with the lapse of time finally produces a coating impenetrable to air and moisture. This adherent film replaces the loose skin of iron above referred to and the enamel-like coating ultimately produced does not show any tendency to peel ofi. Subsequent heat treatment to do away with strains should be low enough to preserve the coating.

Thus not only is the sheet provided with a coating which with the lapse of time finally produces an air and moisture-proof enamel-like coating, but the objectionable feature of a scale on the surface of the completed sheet is done away with. For a sheet which is to be painted the absence of this film is very valuable. As stated in our other applications above referred to, should the coating formed by this process and from having been exposed to atmospheric conditions, become broken; the metal beneath will provide itself with a replacement coating of compounds of iron which are air and moisture-proof. No technical significance is meant for the words annealing and pickling, they being used to mean heat and acid bath treatment, and no more.

The product thus produced has distinctive qualities in that it is of self-protecting base metal and has a produced film of silicious material added to its surface structure. Not only this, but it is a silicon-iron alloy which is annealed and yet has no loosely adherent skin. In the claims, the refer- Having thus described our invention,

what We claim as new and desire to secure by Letters Patent, is:

1. A new and useful annealed iron-silicon alloy sheet, having a surface which comprises silicon compounds physically incorporated with the surface portions of said sheet and forming an impregnated part thereof,

2. A new and annealed iron-silicon alloy body, having a surface which comprises additional silicon compounds physically incorporated with the surface portions of said body so as to form an impregnated part thereof. said silicon compounds comprising those derived from a pickling away of the iron content of the loosely adherent film resulting from annealing of said sheet.

WESLEY J. BECK. JAMES A. AUPPERLE. 

